Rank

Description

Approximate Carbon content

100

Anthracite

95-93%

200

Low volatile steam coal

93-91.5%

300

Prime coking coal

90.5-89

400

 "

89-87

500

Coking /gas coal

87-85

600

 

85-84.5

700

General purpose coal

84.5-83.5

800

High Volatile steam

83.5-81.5

900

 and house coal

81.5-80

Table 1: The British National Coal Board (“NCB”) nine major ranks of coal.